Write me a function called `move` that, given a string x, returns all possible alternate strings y' such that y' is derived from x by moving a substring of x to an arbitrary position
Write me a function called `move` that, given a string x, returns all possible alternate strings y' such that y' is derived from x by moving a substring of x to an arbitrary position
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 | import itertools def move(x): """ Generates all unique strings that can be derived from the input string 'x' by moving one of its contiguous substrings to any possible position within the remaining part of the string. Args: x: The input string. Returns: A set of all unique strings obtainable by the described move operation. This set might include the original string 'x' itself if a move results in reconstructing 'x'. """ n = len(x) results = set() if n == 0: return set() # No substrings to move in an empty string # 1. Iterate through all possible substrings # A substring is defined by its start (i) and end (j) index (exclusive) for i in range(n): for j in range(i + 1, n + 1): substring_to_move = x[i:j] # 2. Determine the remaining part of the string remaining_part = x[:i] + x[j:] len_remaining = len(remaining_part) # 3. Iterate through all possible insertion points for the substring # The substring can be inserted at any index k from 0 to len_remaining for k in range(len_remaining + 1): # 4. Construct the new string new_string = remaining_part[:k] + substring_to_move + remaining_part[k:] results.add(new_string) # Note: The original string 'x' will often be part of the results, # as moving a substring back to its original location is one of the possibilities. # If you strictly want strings *different* from x, you could add: # results.discard(x) # However, the prompt asks for "all possible alternate strings y' such that y' is derived", # which usually includes the original if the derivation process can produce it. return results # --- Example Usage --- print(f"Input: 'abc'") print(f"Output: {move('abc')}") # Expected: {'abc', 'acb', 'bac', 'bca', 'cab', 'cba'} - Wait, cba isn't possible by moving substrings. Let's re-check. # Moving 'a': "abc" -> "bc" -> "abc", "bac", "bca" # Moving 'b': "abc" -> "ac" -> "bac", "abc", "acb" # Moving 'c': "abc" -> "ab" -> "cab", "acb", "abc" # Moving 'ab': "abc" -> "c" -> "abc", "cab" # Moving 'bc': "abc" -> "a" -> "bca", "abc" # Moving 'abc': "abc" -> "" -> "abc" # Unique results: {'abc', 'bac', 'bca', 'acb', 'cab'} - Corrected expected output. print("-" * 20) print(f"Input: 'a'") print(f"Output: {move('a')}") # Expected: {'a'} # Moving 'a': "a" -> "" -> "a" print("-" * 20) print(f"Input: ''") print(f"Output: {move('')}") # Expected: set() print("-" * 20) print(f"Input: 'aabb'") print(f"Output: {move('aabb')}") # Example derivations: # move 'a' (first one): "abb" -> "aabb", "aabb", "ab ab", "abba" # move 'b' (first one): "aab" -> "baab", "abaab", "aab b", "aabb" # move 'aa': "bb" -> "aabb", "ab ab", "bbaa" # move 'ab': "ab" -> "abab", "a abb", "ab ab" # ... and many more # Expected: {'aabb', 'abab', 'abba', 'baab', 'baba', 'bbaa'} |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 | import itertools def move(x): """ Generates all unique strings that can be derived from the input string 'x' by moving one of its contiguous substrings to any possible position within the remaining part of the string. Args: x: The input string. Returns: A set of all unique strings obtainable by the described move operation. This set might include the original string 'x' itself if a move results in reconstructing 'x'. """ n = len(x) results = set() if n == 0: return set() # No substrings to move in an empty string # 1. Iterate through all possible substrings # A substring is defined by its start (i) and end (j) index (exclusive) for i in range(n): for j in range(i + 1, n + 1): substring_to_move = x[i:j] # 2. Determine the remaining part of the string remaining_part = x[:i] + x[j:] len_remaining = len(remaining_part) # 3. Iterate through all possible insertion points for the substring # The substring can be inserted at any index k from 0 to len_remaining for k in range(len_remaining + 1): # 4. Construct the new string new_string = remaining_part[:k] + substring_to_move + remaining_part[k:] results.add(new_string) # Note: The original string 'x' will often be part of the results, # as moving a substring back to its original location is one of the possibilities. # If you strictly want strings *different* from x, you could add: # results.discard(x) # However, the prompt asks for "all possible alternate strings y' such that y' is derived", # which usually includes the original if the derivation process can produce it. return results # --- Example Usage --- print(f"Input: 'abc'") print(f"Output: {move('abc')}") # Expected: {'abc', 'acb', 'bac', 'bca', 'cab', 'cba'} - Wait, cba isn't possible by moving substrings. Let's re-check. # Moving 'a': "abc" -> "bc" -> "abc", "bac", "bca" # Moving 'b': "abc" -> "ac" -> "bac", "abc", "acb" # Moving 'c': "abc" -> "ab" -> "cab", "acb", "abc" # Moving 'ab': "abc" -> "c" -> "abc", "cab" # Moving 'bc': "abc" -> "a" -> "bca", "abc" # Moving 'abc': "abc" -> "" -> "abc" # Unique results: {'abc', 'bac', 'bca', 'acb', 'cab'} - Corrected expected output. print("-" * 20) print(f"Input: 'a'") print(f"Output: {move('a')}") # Expected: {'a'} # Moving 'a': "a" -> "" -> "a" print("-" * 20) print(f"Input: ''") print(f"Output: {move('')}") # Expected: set() print("-" * 20) print(f"Input: 'aabb'") print(f"Output: {move('aabb')}") # Example derivations: # move 'a' (first one): "abb" -> "aabb", "aabb", "ab ab", "abba" # move 'b' (first one): "aab" -> "baab", "abaab", "aab b", "aabb" # move 'aa': "bb" -> "aabb", "ab ab", "bbaa" # move 'ab': "ab" -> "abab", "a abb", "ab ab" # ... and many more # Expected: {'aabb', 'abab', 'abba', 'baab', 'baba', 'bbaa'} |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 | import itertools def move(x): """ Generates all unique strings that can be derived from the input string 'x' by moving one of its contiguous substrings to any possible position within the remaining part of the string. Args: x: The input string. Returns: A set of all unique strings obtainable by the described move operation. This set might include the original string 'x' itself if a move results in reconstructing 'x'. """ n = len(x) results = set() if n == 0: return set() # No substrings to move in an empty string # 1. Iterate through all possible substrings # A substring is defined by its start (i) and end (j) index (exclusive) for i in range(n): for j in range(i + 1, n + 1): substring_to_move = x[i:j] # 2. Determine the remaining part of the string remaining_part = x[:i] + x[j:] len_remaining = len(remaining_part) # 3. Iterate through all possible insertion points for the substring # The substring can be inserted at any index k from 0 to len_remaining for k in range(len_remaining + 1): # 4. Construct the new string new_string = remaining_part[:k] + substring_to_move + remaining_part[k:] results.add(new_string) # Note: The original string 'x' will often be part of the results, # as moving a substring back to its original location is one of the possibilities. # If you strictly want strings *different* from x, you could add: # results.discard(x) # However, the prompt asks for "all possible alternate strings y' such that y' is derived", # which usually includes the original if the derivation process can produce it. return results # --- Example Usage --- print(f"Input: 'abc'") print(f"Output: {move('abc')}") # Expected: {'abc', 'acb', 'bac', 'bca', 'cab', 'cba'} - Wait, cba isn't possible by moving substrings. Let's re-check. # Moving 'a': "abc" -> "bc" -> "abc", "bac", "bca" # Moving 'b': "abc" -> "ac" -> "bac", "abc", "acb" # Moving 'c': "abc" -> "ab" -> "cab", "acb", "abc" # Moving 'ab': "abc" -> "c" -> "abc", "cab" # Moving 'bc': "abc" -> "a" -> "bca", "abc" # Moving 'abc': "abc" -> "" -> "abc" # Unique results: {'abc', 'bac', 'bca', 'acb', 'cab'} - Corrected expected output. print("-" * 20) print(f"Input: 'a'") print(f"Output: {move('a')}") # Expected: {'a'} # Moving 'a': "a" -> "" -> "a" print("-" * 20) print(f"Input: ''") print(f"Output: {move('')}") # Expected: set() print("-" * 20) print(f"Input: 'aabb'") print(f"Output: {move('aabb')}") # Example derivations: # move 'a' (first one): "abb" -> "aabb", "aabb", "ab ab", "abba" # move 'b' (first one): "aab" -> "baab", "abaab", "aab b", "aabb" # move 'aa': "bb" -> "aabb", "ab ab", "bbaa" # move 'ab': "ab" -> "abab", "a abb", "ab ab" # ... and many more # Expected: {'aabb', 'abab', 'abba', 'baab', 'baba', 'bbaa'} answer = set(move('abcdef')) expected = set(['abcdef', 'abcdfe', 'abcedf', 'abcefd', 'abcfde', 'abdcef', 'abdecf', 'abdefc', 'abecdf', 'abefcd', 'abfcde', 'acbdef', 'acdbef', 'acdebf', 'acdefb', 'adbcef', 'adebcf', 'adefbc', 'aebcdf', 'aefbcd', 'afbcde', 'bacdef', 'bcadef', 'bcdaef', 'bcdeaf', 'bcdefa', 'cabdef', 'cdabef', 'cdeabf', 'cdefab', 'dabcef', 'deabcf', 'defabc', 'eabcdf', 'efabcd', 'fabcde']) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
1 2 3 4 5 6 7 8 9 10 11 12 | Input: 'abc' Output: {'abc', 'cab', 'bca', 'acb', 'bac'}</p> <hr /> <p>Input: 'a' Output: {'a'}</p> <hr /> <p>Input: '' Output: set()</p> <hr /> <p>Input: 'aabb' Output: {'bbaa', 'abba', 'aabb', 'abab', 'baab'} All tests passed |
Testing if the previous output contains the string All tests passed
: True